A and B can complete a work in 12 days. B and C can complete the same work in 18 days. C and A can complete in 24 days. How many days will take for A, B and C combined together to complete the same amount of work?

A contractor is doing work for 7 days at your home. You need to pay him $7000 in total. Every day you need to pay him $1000. To pay him you have a gold plate worth $7000. But you can only cut it twice, how will you achieve it?